A previously known assembling means for fixing of tubes having four sides, hereafter called square tubes, comprises a portion of a U-profile, i. e. having a bottom and two protruding flanges where the bottom is provided with holes for fixing means, such as fixing screws. The bottom is screwed onto the outside of a square tube, and the two flanges are put into the end of another square tube.

In one of the flanges there is a threaded hole, which extends transversally to the plane of the flange. In this a tension screw is provided whose end, opposite the head of the screw, abuts the inside of the other flange. A hole is made in the square tube in line with the tension screw. When the tension screw is screwed inwards the distance between the flanges becomes larger so that the assembling means will be tightened fixedly in the tube.

A problem with the known assembling link is that the flanges is bent outwards, i. e. a rotation around the bottom occurs which causes only the outer ends of the flanges to abut the inside of the tube. Therefore, the flanges must be heavily stretched out for the assembling means to keep in place since such a small surface abuts the inside of the tube.

Additionally, this construction is weaker since the flanges will bend when loaded since the assembling means does not fill up the volume of the tube. Another drawback is that the known assembling link is extruded in a direction which gives drawbacks when providing and loading of holes for screws.

An object of the present invention is to provide a secure assembly which does not require extreme tension forces in the tension screw.

This object is met by a device according to the preamble characterised in that the inner cross-section shape of the tube with at least two opposite surfaces mainly corresponds to the shape of two opposite surfaces of the assembling means, which further comprises a tension plate with a threaded through hole, arranged orthogonally to the plane of the tension plate, for co-operation with the tension screw, the tension plate is parallelly displaceable towards the inside of the tube in question or one of the opposite surfaces of the tube when tightening the tension screw in and for-fixation of the assembling means in the tube.

As a basis for the invention is the insight that to obtain as large contact area as possible to the insides of the tube, a parallel displacement must be effected by the assembling means, whereby the frictional force may be used in a higher degree for the sustaining of the assembling means inside the tube and less pressure force is needed.

Preferably, the body is provided with a recess for receiving the tension plate. This facilitates substantially when mounting since the tension plate easily is held in place by the recess.

Preferred embodiments of the present invention will now be illustrated and described in connection of the enclosed drawing, in which: Fig. 1 illustrates in an exploded view assembling means according to the present invention provided on a tube for further fixation in a second tube.

Fig. 2 illustrates the body of the assembling means according to fig. 1 in a perspective view with four alternative details for fixation.

Fig. 3 illustrates a second embodiment of the body of the assembling means.

Fig. 4 illustrates a third embodiment of the assembling means according to the present invention with two different fixing means integrated in the assembling means.

Fig. 5 illustrates a fourth embodiment of the assembling means of the present invention with an extension at which another assembling means may be mounted.

Fig. 1 shows assembling means according to the present invention comprising a body 1, a tension plate 2 and a tension screw 3. The body 1 is provided with recesses 4 in one of its ends, see fig. 2, which recesses 4 are arranged substantially orthogonally to the end, for co-operation with fixing means,. such as screws, for fixing at, for example, the outside of a square tube to be assembled with the end of another square tube.

The recesses 4 may be threaded or be thin bores for self- tapping screws. Preferably, a recess 5 is provided along one of the side edges of the body for receiving the tension plate 2. Additionally, the body 1 is preferably provided with large support surfaces for abutment with a through hole 7 which is orthogonally arranged to the plane of the tension plate 2 and provided with an internal thread. The hole 7 is preferably positioned centrally.

The tension plate 2 is intended to fit in the recess 5 as the side of the side of the body 1 so that it, does not protrudes outside the side of the body 1. The tension screw 3, provided with a head end 8 and an opposite end 9, is intended to be

screwed into the hole 7. The tension screw 3 is preferably relatively thick compared to its length.

In fig. 1 the body is attached to a square tube 6. The tension screw 3 is screwed into the hole 7 in the tension plate 2 and the tension plate 2 is placed in the recess 5 in the side of the body 1. Thereafter, the end of the square tube 10 to be attached is passed over the assembling means, i. e. the body 1, the tension plate 2 and the tension screw 3.

In the square tube 10, a hole 11 is made which will be in line the tension screw 3 when the square tube 10 is positioned for fixation. The tension screw 3 is screwed in so that it abuts with its end 9 the body 1 and is tightened, the tension plate 2 is parallelly displaced away from the body 1 so that it protrudes outside the sidewall of the body 1 and thus tighten against the inside of the square tube 10.

In fig. 3 a second embodiment of the body 1 of the assembling means is shown. In this the recess 5 for the tension plate 2 is provided in one of the end sides of the body 1.

To obtain best possible support and fixation the cross- section of the assembling means it should fill out the inner space of the square tube. Of course material saving recesses may be present, see the embodiment according to fig. 3, but the larger the surface that is in contact with the insides of the square tube the more solid the fixation will be.

In the end of the assembling means that is provided with recesses details may be provided instead of square tubes, see fig. 2. For example, it is possible by means of the assembling means to attach wheels in the ends of square tubes, or hinges and so on. Of course it is possible to use the assembling means to attach a square tube to any surface, for example a table top.

In fig. 4 a third embodiment of the assembling means according to the invention where the assembling means is integrally provided with, for example, a part 12 of a hinge to be or any other fixing means 13.

In fig. 5 a fourth embodiment of the assembling means according to the invention is shown where the assembling means is extended and provided with through holes 14 for mounting of another assembling means by means of, for example, screws.

In order to facilitate the making of holes and mounting in the square tubes a mounting jig may be used.

A number of embodiments of the present invention have been described and illustrated but of course the assembling means may have lots of different embodiments. For example it may be contemplated a cylindrical assembling means. The invention is not limited to the shown embodiments but is defined by the following claims.